Method and apparatus for dewatering mineral concentrates



July l1, 1944. F. TROTTER METHOD AND APPARATUS FOR DEWATERING-MINERALCONCENTRATES Filed March 26, 1941 VSBRATOR INVENTOR FRANK TROTTEQPatented,s July 11,'. f

f UNITED? METHOD AND, APPARATUS FOR DEWATERI-z ING CONCENTRATESil FrankTrotter, or'istacubaassignor. to Cuban# American Manganese- Corporation;N` w; York; 5 N. .,a corporation offllelaware- Vapplicati@ March 2s,1941; serialNo. 385,259

s claims. (ci. 21o-55) This invention relates to processes fordewatering mineral concentrates, and to anappar'atus in which saidprocesses may be carried out..

The most common method ofdewateringcon-y centrates composed ofparticles. of 28.mi cro ns and smallersizes, now being. used in mineralre;

covery. involves, firstly, dewatering as` far. as possible by subjectingthe same to. settling or thickeningin suitable tanks and, secondly,vlterf ing the thickened mass through a-porousy medi-- um suchy asv nelywoven cloth or otherporous substance contained in any one of zalnumberlof conventionalv mechanical -lter devices..

the mass, although the mass-after the `dewatering operationappears to bequite dry. Theoceluded water adhering lto the concentrates isdisadvantageous not only with respect, to the subsequent recoverytreatment given the same, vbut .also with respect'tofreight costs whichare funnecessarily high, and toleakage from thecars duringtransportation due to the water present,

The lobject of the present inventlon,s.to pro-,- vide methods ofdewatering; concentrates-,Which not only are quicker and cheapertooperatethan.

commercial prior processes but which also remoye a greater proportion ofWater. water content means lower \freight costs vand avoidance ofleakage from cars used in transportation. A further object is to providean zap.- paratus in which the rprocess .may be carriedcut with the nimumof handling, ata lowcost, and in a short period of time. Y

InV accordance with the preferred embodiment, the process of the presentinventioninvolves-subjecting the concentrates. to thev action.` ofastream, or streams, of compressedairfora `peri-` od of a few minuteswherebyv the occluded water adhering to the particles is causedto.coalesce and to become separable therefrom, after which it will befound that the liberated Waterfwill readily rise to the surface in ashort while.. .The water which rises to the top of lthe mass ,may

then be readily drawn off by decantingdphon-L ing, orthrough the actionof pumps.. 'I'l'leeffec-y tiveness of the compressed air is believedpri.-

marily due to a rapid vibration and agitation of the mass on theparticles therein. The principal action of the air in causingthemovementis the' formation of myriads of air bubbles which .are

forced up through the mass by othenbubbles constantly being formed..

In accordance with another embodiment of 55 This, treatment has Abeenfound incomplete- V inthe treatment of some concentrates,due,to;theadhesion and retention ofV part ,ofV the-.water within` Witlrreference tothedrawing; Figure f1 is an. i

theinvention, thev mass of concentrates. contained in ai tankisvibratedby meansv chame-l chanical. vibrator of `any suitableconstruction acting directly on the l tank. pects; the invention;comprehends vthe simultaneous `or supplementary'vuse of bothtypesof-vibratingmeanse Thev process of Vthe present invention may bereadily understood by' reference,y tothezaccoms `panying drawing inwhich thereis -diagrammati-H cally illustratedan apparatus in whichtheprocess-.may be effectivelycarriedyout elevation; and Figure-2..isa:p1an1view.

In the'. :apparatus illustrated there'.V istshown, a:

leakfproof. tank. or container: IIJ having: an loperi top --for the,introduction of the vconcentrates yto v be dewatered" Thetank isprovidedwith a dis charge mechanism composedof a screw conveyor.lHadapted to vconvey the treatedconcentrates tov the dischargeoutletl2.=provided'with.a.leak- The reduction in 1 causedv byvtheVcompressed:airethe air is shut* on.

If 1the Whole ,body oficoncentratesis' not vibrated adequately,athe; airpipev I5ifis' shifted.- to-otherH positionsiin; theimass rand .theprocess repeated.. Thereafter .themass is permittedV to settle.. Whenproof closure'gl3.f. The tank Illmay bez-rectangular vor` of any other'suitablesh'ap andthe-dis'-v .charge mechanism :should beoffsufli'cientfsize, or Y duplicatedbyfaj sufcienti number, todis'ch'argvefv the -tank contentswithin'saxshort nperiod offtime.

Included withthe apparatus is an .air pump' 1I 4 or other sourcegof vairpressure connected through 1 a valvedLv conduit: I 5l "terminating,within -thetank- I 0, .which conduit may j or may not be.' Vpermanentlyattached lto.; the.; tankwall,` Thetankf l 0 may y alsoV halle attachedto; a wallv thereof ay vi'- brator, I8 connected to. the-air pump:Il'through Nearrthetop-Jof they the valved, connectiomxl T. tank IU"there arefthreevalved-outlets lratsdifferent levels. 7

In. carryingbut .the process of fthe present in*- vention in the:illustrated apparatus the 'Y outlet preferably abovel the Ahighestoutlet :|8.

In. its broader lasf be seen emerging at the surface.

permitted to settle.

the water rises to the top it is decanted ofi' through one or more ofthe valved oulets I8.

nally, the discharge outlet l2 is opened and the Y screw conveyor Il isactuated toiorce out of the tank the dewatered concentrates which are inthe form of a solid mass, l. e., a non-duid or non-nowable mass. Y Y

AlthoughV a single treatment in this manner isl usually sulllcient, theoperation may be repeated if additional water can thereby be released.Thev normal vibration of the mass by thev direct introduction ofcompressed air may be assisted either by` using a pulsating stream ofair from a reciprocating compressor. or, by using themechanicalvibrator' il which in operation causes the tank itself to vibrate aswell as the concenastaeos dryness trates would immediately sink to thebottom.

A fter settling, the water which rose was drawn oi! and the dewateredconcentrates were discharged.

Although the foregoingexamples describe the applicationof the process ofthe instant invenf tion to concentrates which have already beenilltrates. In the treatment of specic concentrates` it may be found moreeilective to use the mechanical vibrator I6 alone, without usingcompressed air directly through the conduit Il. Generally, however,streamof compressed air directly within the concentrates gives the mosteffective results, l for through the use of the alr in this manner amore thorough and quicker agitation isv obtained ata lower cost. Thevibration treatment in either case results in the formation of longtubular vertical channelsin `the concentrates through which the waterrises to the top.

. Y If a continuous dewatering operation isY desired to take care of asteady supply of concentrates,

vibration generated -by a' a series of tanksmay be provided, or a singletank divided into three or more compartments may -be employed andthesame operated such a that one tank or compartment isl being filled whilea second one is being vibrated anda third is being discharged.V

q 1 V Examples `Example 1.-*-Manganese mineral having a vparticle sizeof 1000 microns down to 0.5 micron alter being separated from itsganguefby flotation is rst settled ina large drag conveyor to remove thereadily separable water. Therthickened mineral containing about'30%moisture is then conveyedto the tank lll,V .whereupon the mass issubjected to.a vibrationtreatment by means of. compressed airunder 90pounds pressure for a period of about 3 minutes,'the air beingintroduced through the conduit l5.l The mass was then permitted tosettle, and during such period Vvertical passages of about one-quarterof an inch in diameter formed, through which water could The supernatantwater was then de'canted off, leaving a mass containing aboutl8% ofwater. ,Y

`Example 2.-Manganese mineral separated from its gangue `by flotation,was settled to remove a portion of the water, and vacuum filtered toremove an additional quantity of water." The' resulting partiallydewatered filterV cake containing 25% of water was introduced into'thetank I0 and subjected to vibration in the manner de'- scribed in4Example l.v Thereafterthe mass was The water which rose to the topwasthen decanted off. Finally, the mass was discharged from the tank and`upon tesi;v` was found to contain only 18% water. Y Y i l Example 3.-Acomplex' lead, gold,v silver Yand copper concentrateY separated fromitsgangueV by *.flotation and thickeneclinv a thickener tank, was

further dewatered by meansof a rotary c ontinuous vacuum filter using aspecial'woven can'- vas as a ltering medium. The concentrates discharged'from the lter possessed an apparent tered to remove a major portion'oithe water, it should be understood that the process is applicable toconcentrates which have not been previously dewatered by illtering orequivalent treatment.

The process and the apparatus of the present invention are particularlydesigned for the treatment of mineral concentrates, and are especiallyintended for the treatment of concentrates obtained by notation, but theprocess and apparatus are suitable for the treatment of any mass ofparticles containing water held within the .material in such manner asto resist the force of conventional commercial separating devices.Materials having particles of 1000 microns and smaller respond readilyto the treatment.

It should be understood that the present invention is not limited to thespecific steps or apparatus shown'V but extends to all equivalents whichwill occur to those skilled in the art upon water.

2. The process of dewatering mineral concentrates which comprisesremoving adherent water by vibrating a mass of such concentrates untilthe adhesion is disrupted, and thereafter gravita- Ationally separatingthe concentrates in a solid, Vncn-flowable form from the supernatantwater.

3. The process of removing occluded water fro'ml flotation concentrateswhich comprises introducing Ycompressed air into said concentrates f tocause vibration of the same.whereby the adhesion between theoccludedwater and the concentrates is disrupted, and drawing off thewater which separates from the concentrates.

4. The process of removing occluded water from otation concentrateswhich comprises vibrating a mass of such concentrates by means Yof astream of compressed air until vertical channels will form -therein onsettling, settling said mass and separating the Water which rises to thesurface.

y5. The process of' removing occluded water from mineral concentrateswhich comprises introducing a pulsating stream of compressed air into amass of said concentrates until the oc clude'd water will separate onstanding, settling the mass whereby released water rises to the top,andseparating the water.

6. The process of 'removing occluded .water from a mass of notationconcentrates in a container which comprises vibrating said containermences to rise to the surface. thereafter settling the mass and removingthe supernatant water.

8. An apparatus for dewatering flotation concentrates which comprises atank, an opening therein for the introduction ot concentrates,

means for introducing a stream of compressed air nearthe bottom thereof,means for drawing of! water near the top thereof, and means fordischarging dried non-nowable concentrates FRANK TROT'IER.

l0 therefrom.

